Complex antenna

ABSTRACT

Provided is a complex antenna which corresponds to both a circularly polarized wave and a linearly polarized wave. The complex antenna includes a substrate, a power feed terminal, four helical antenna devices disposed on the substrate at intervals of 90 degrees, four delay lines having different lengths by a quarter wavelength, and four switch modules which are connected to the power feed terminal in common and each of which is connected to each helical antenna device and each delay line. Each switch module selects one of a first mode in which the power feed terminal and each helical antenna device are directly connected and a second mode in which each delay line is connected to each helical antenna device so that a power feed phase feed from the power feed terminal and propagated to each delay line can be sequentially shifted by 90 degrees.

PRIORITY

This application claims the benefit of Japanese Patent Application No.2005-364743, filed on Dec. 19, 2005, in the Japanese IntellectualProperty Office, and Korean Patent Application No.10-2006-0078912, filedon Aug. 21, 2006, in the Korean Intellectual Property Office, thecontents of both of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a complex antenna, and moreparticularly, to a complex antenna which corresponds to both acircularly polarized wave and a linearly polarized wave.

2. Description of the Related Art

Portable wireless devices which are capable of making communicationsusing a satellite, such as Global Positioning Systems (GPS) phones andPersonal Data Assistants (PDA), are increasingly popular and necessary.For example, there are safety advantages such as a user being able toimmediately send exact position information obtained by using a GPSsatellite to a police or fire station via a mobile phone base station inan emergency. In addition, satellite radio using a broadcastingsatellite has good sound quality, many channels and a wide coveragearea. Thus, a rapid proliferation of GPS or satellite radio is expected.

Antennas in which both ground communication and satellite communicationare possible are needed in the above-described usages.

Since the GPS or satellite radio has circularly polarized waves, a patchantenna or a four-wire helical antenna is used therein. Since mobilephones or wireless Local Area Networks (LAN) have linearly polarizedwaves, a monopole antenna is used therein.

A technique of an antenna which corresponds to both a circularlypolarized wave and a linearly polarized wave is disclosed in JapanesePatent Laid-open Publication No. 2002-314312. According to thisdisclosure, a monopole antenna is disposed in the vicinity of the centeraxis of a four-wire helical antenna and both of the antennas correspondto a circularly polarized wave and a linearly polarized wave. However,this combination causes a miniaturization effect, which is detrimentalto the antenna performance.

SUMMARY OF THE INVENTION

The present invention provides a complex antenna which corresponds toboth a circularly polarized wave and a linearly polarized wave.

According to the present invention, there is provided a complex antennawhich includes a substrate, a power feed terminal provided at one sideof the substrate, four helical antenna devices disposed on the substrateat intervals of 90 degrees centering on a first axis perpendicular tothe substrate, four delay lines having different lengths by a quarterwavelength, and four switch modules which are connected to the powerfeed terminal in common and each of which is connected to each helicalantenna device and each delay line, wherein each switch module selectsone of a first mode in which the power feed terminal and each helicalantenna device are directly connected and a second mode in which eachdelay line is connected to each helical antenna device so that a powerfeed phase feed from the power feed terminal and propagated to eachdelay line can be sequentially dislocated by 90 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the present invention will become moreapparent by a detailed description of the preferred embodiments thereofwith reference to the attached drawings in which:

FIG. 1 is a perspective view of a complex antenna according to a firstembodiment of the present invention;

FIG. 2 is a view of an antenna feed network according to the presentinvention;

FIG. 3A is a view illustrating the state of a switch module in the caseof a linearly polarized wave;

FIG. 3B is a view illustrating the state of a switch module in the caseof a circularly polarized wave;

FIG. 4 is a plan view illustrating an arrangement design of a PrintedCircuit Board (PCB) of the antenna feed network;

FIG. 5 is a perspective view of the PCB;

FIG. 6 is a perspective view of a complex antenna according to a secondembodiment of the present invention; and

FIG. 7 is a perspective view of a complex antenna according to a thirdembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention will bedescribed with reference to the accompanying drawings. It is to be notedthat the same elements are indicated with the same reference numeralsthroughout the drawings. In the following description of the presentinvention, a detailed description of known functions and configurationsincorporated herein will be omitted when it may obscure the subjectmatter of the present invention.

FIG. 1 is a perspective view of a complex antenna according to a firstembodiment of the present invention. The complex antenna of FIG. 1includes a PCB 48, a power feed terminal P0, first through fourthhelical antenna devices 40, 42, 44 and 46, first through fourth switchmodules 20, 22, 24 and 26 and first through fourth delay lines 30, 32,34 and 36.

Each of the first through fourth helical antenna devices 40, 42, 44 and46 includes conductors. The first through fourth helical antenna devices40, 42, 44 and 46 extend spirally in a ceiling direction in which apitch angle is preferably in the range of 30-60 degrees. Each of thefirst through fourth helical antenna devices 40, 42, 44, and 46 isdisposed concentrically on the PCB 48 at intervals of 90 degrees. Inaddition, the first through fourth switch modules 20, 22, 24 and 26 andthe first through fourth delay lines 30, 32, 34 and 36 are disposed onthe PCB 48. The first through fourth switch modules 20, 22, 24 and 26control a connection with the first through fourth delay lines 30, 32,34 and 36.

Since the outer diameter, length and pitch angle of spirals of the firstthrough fourth helical antenna devices 40, 42, 44 and 46 directly affectproperties such as radiation patterns of an antenna or gains, the firstthrough fourth helical antenna devices 40, 42, 44 and 46 can be properlydesigned according to requirements. A good conductor such as aluminum orcopper alloy is used for the first through fourth helical antennadevices 40, 42, 44 and 46.

An antenna feed network which constitutes an electrical circuit betweeneach of the first through fourth helical antenna devices 40, 42, 44 and46 and the power feed terminal P0, is provided on the PCB 48. The firstthrough fourth switch modules 20, 22, 24 and 26 which control aconnection with each of the first through fourth delay lines 30, 32, 34and 36, are disposed on the antenna feed network.

The antenna feed network may be provided on the PCB 48. Thus, the PCB 48may be set to the size at which all of antenna feed networks can beinstalled. More preferably, the diameter of the PCB 48 is in the rangeof one time to three times of the outer diameter of a spiral of each ofthe first through fourth helical antenna devices 40, 42, 44 and 46.

FIG. 2 is a view of an antenna feed network according to the presentinvention.

The first through fourth switch modules 20, 22, 24 and 26 which areprovided between each of the first through fourth helical antennadevices 40, 42, 44 and 46 and the power feed terminal P0 and controlconnection with each of the first through fourth delay lines 30, 32, 34and 36, are disposed on the antenna feed network.

The power feed terminal P0 is connected to a power feed unit (not shown)and a driving power is inputted to the power feed terminal P0. Thelength of the first delay line 30 is referred to as L1. The length L2 ofthe second delay line 32 is set to L1+λ/4, the length L3 of the thirddelay line 34 is set to L2+λ/4 and the length L4 of the fourth delayline is set to L3+λ/4, respectively. Here, λ is a wavelength on thefirst through fourth delay lines 30, 32, 34 and 36 of electromagneticwaves transmitted through the first through fourth delay lines 30, 32,34 and 36.

First through fourth antenna terminals P1, P2, P3 and P4 are provided onthe antenna feed network to be connected to arms of the first throughfourth helical antenna devices 40, 42, 44 and 46. As a result, the powerfeed phases of the first through fourth helical antenna devices 40, 42,44 and 46 to which power is fed via the first through fourth delay lines30, 32, 34 and 36 are sequentially delayed at 90 degrees. A micro stripline may be used as the first through fourth delay lines 30, 32, 34 and36.

FIGS. 3A and 3 B are views illustrating a first mode and a second moderespectively, switching states of the first through fourth switchmodules 20, 22, 24 and 26.

First through fourth switch terminals A, B, C and D are provided on thefirst through fourth switch modules 20, 22, 24 and 26 and switched intoone of the first mode and the second mode as illustrated in FIGS. 3A and3 B.

For example, the first switch terminal A is connected to the power feedterminal P0 by a wire on the PCB 48. The second switch terminal B isconnected to each of the first through fourth antenna terminals P1, P2,P3 and P4 by wires on the PCB 48 and then is connected to each of thefirst through fourth helical antenna devices 40, 42, 44 and 46. Thethird switch terminal C is connected to one end of each of the firstthrough fourth delay lines 30, 32, 34 and 36, and the fourth switchterminal D is connected to the other end of each of the first throughfourth delay lines 30, 32, 34 and 36.

When transmitting and receiving a linearly polarized wave, the firstthrough fourth switch modules 20, 22, 24 and 26 are switched into thefirst mode. That is, a circuit to the first through fourth delay lines30, 32, 34 and 36 is opened and the first through fourth helical antennadevices 40, 42, 44 and 46 are positioned on the same phase, asillustrated in FIG. 3A.

Meanwhile, when transmitting and receiving or only receiving acircularly polarized wave, the first through fourth switch modules 20,22, 24 and 26 are switched into the second mode and a phase of eachhelical antenna device is shifted by 90 degrees. The lengths of thefirst through fourth delay lines 30, 32, 34 and 36 are increased by aquarter wavelength from the first antenna terminal P1 to the fourthantenna terminal P4. In this case, the first through fourth switchmodules 20, 22, 24 and 26 are converted, as illustrated in FIG. 3B, soas to connect the power feed terminal P0 to one end of the first throughfourth delay lines 30, 32, 34 and 36. Similarly, the first throughfourth switch modules 20, 22, 24 and 26 are converted, as illustrated inFIG. 3B, so as to connect the first through fourth antenna terminals P1,P2, P3 and P4 to the other end of each of the first through fourth delaylines 30, 32, 34 and 36. PIN structure semiconductor devices may be usedas the first through fourth switch modules 20, 22, 24 and 26.

Table 1 shows power feed phases of the first through fourth antennaterminals P1, P2, P3 and P4 in the cases of a linearly polarized waveand a circularly polarized wave, respectively. When the linearlypolarized wave is driven, the first through fourth antenna terminals P1,P2, P3 and P4 are positioned on the same phase a (degrees). When thecircularly polarized wave is driven and the phase of the first antennadevice P1 is β (degrees), the phase of the second antenna terminal P2 isβ+90 (degrees), the phase of the third antenna terminal P3 is β+180(degrees) and the phase of the fourth antenna terminal P4 is β+270(degrees). In this case, all amplitudes of the first through fourthantenna terminals P1, P2, P3 and P4 are the same. TABLE 1 Power feedphases (degrees) Power feed conditions P1 P2 P3 P4 When linearlypolarized wave is α α α α driven When circularly polarized wave is β β +90 β + 180 β + 270 driven

In addition, when high precision is not required in amplitude and phase,the first switch module 20 and the first delay line 30 may be omitted.However, the first switch module 20 always connects the first delay line30 having the length of 0, the power feed terminal P0 and the firstantenna terminal P1. In addition, when high precision is required inamplitudes, an amplitude adjusting attenuator may be added to the firstthrough fourth delay lines 30, 32, 34, 36.

FIG. 4 is a plan view of the arrangement of the PCB 48. The power feedterminal P0 is disposed in the vicinity of a center of the PCB 48. Thefirst through fourth antenna terminals P1, P2, P3 and P4 are disposed ona concentric circle centering on the power feed terminal P0 at about 90degrees.

The first switch module 20 is disposed in the middle of the firstthrough fourth antenna terminals P1, P2, P3 and P4, the first switchterminal A is connected to the power feed terminal P0, the second switchterminal B is connected to the first antenna terminal P1, the thirdswitch terminal C is connected to one end of the first delay line 30 andthe fourth switch terminal D is connected to the other end of the firstdelay line 30, respectively. Here, if the first through fourth delaylines 30, 32, 34 and 36 can be connected to the third switch terminal Cand the fourth switch terminal D, the arrangement of the first throughfourth delay lines 30, 32, 34 and 36 is not limited to the drawing.Hereinafter, the second switch module 22, the third switch module 24 andthe fourth switch module 26 are disposed in the same manner.

FIG. 5 is a perspective view of the PCB 48. Each of the first throughfourth helical antenna devices 40, 42, 44 and 46 is connected to each ofthe first through fourth antenna terminals P1, P2, P3 and P4 of the PCB48 to extend in a ceiling direction in a spiral shape, therebyconstituting the complex antenna illustrated in FIG. 1. In thearrangement design of the PCB 48, the area of a circuit can be less thanthe half of the area of a construction of a conventional T-shapeddistributor and a conventional delay line. Thus, the complex antenna canbe made small.

In addition, the power feed terminal P0 is connected to a wirelesssystem using a circularly polarized wave and a wireless system using alinearly polarized wave through a branching filter and a switch. Byarranging such a front end at a rear surface of the PCB 48 (i.e., theantenna feed network), a more complex antenna can be made smaller.

The complex antenna having the above structure uses a helical antennadevice for a circularly polarized wave and a helical antenna device fora linearly polarized wave in common. As a result, a monopole antennadoes not need to be separately provided. In addition, even though thecomplex antenna has the same size as that of a conventional four-armhelical antenna, it corresponds to both a circularly polarized wave anda linearly polarized wave. Thus, miniaturization of the complex antennacan be implemented. Furthermore, one power feed terminal (i.e., anantenna input/output port) is provided as marked by reference numeral P0of FIG. 1 so that a connection between the wireless system and the frontend can be simplified and the complex antenna can be made smaller.

The helical antenna device illustrated in FIG. 1 is constructed, forexample, of thin plate-shaped conductors. More preferably, the helicalantenna device is formed of a good conductor and is not limited to thethin plate shape. A structure for winding a conductor around acylindrical dielectric 50 is used to increase a mechanical strength.

FIG. 6 is a perspective view of a complex antenna according to a secondembodiment of the present invention.

A conductor is wound around the cylindrical dielectric 50 at a pitchangle in the range of about 30-60 degrees. The cylindrical dielectric 50is fixed on the PCB 48 so that the mechanical strengths of the firstthrough fourth helical antenna devices 40, 42, 44 and 46 increase. Inthis case, if a groove is formed in advance on the surface of thecylindrical dielectric 50 as will be described later, the first throughfourth helical antenna devices 40, 42, 44 and 46 can be more easilyfixed on the PCB 48.

Meanwhile, as illustrated in FIG. 4, since the first through fourthswitch modules 20, 22, 24 and 26 are disposed between the power feedterminal P0 and each of the first through fourth antenna terminals P1,P2, P3 and P4 and an end of a circumference of the cylindricaldielectric 50 is adjacent to the first through fourth antenna terminalsP1, P2, P3 and P4, the first through fourth switch modules 20, 22, 24and 26 are within the diameter of the cylindrical dielectric 50.

FIG. 7 is a perspective view of a complex antenna according to a thirdembodiment of the present invention. The first through fourth helicalantenna devices 40, 42, 44 and 46 are wound in a spiral shape around asupport 52 which stands on the PCB 48. An insulator of the support 52 isformed in a mesh shape. In this case, the mesh pattern is not limited tothe pattern illustrated in FIG. 1. The entire frame of the support 52 iscylindrical shaped. The first through fourth helical antenna devices 40,42, 44 and 46 are supported by the support 52, so that the complexantenna has a light weight and an improved mechanical strength. Thefirst through fourth switch modules 20, 22, 24 and 26 are disposedbetween the power feed terminal (P0 of FIG. 4) and each of the firstthrough fourth antenna terminals P1, P2, P3 and P4 as shown in FIG. 6,and an end of a circumference of the support 52 is adjacent to the firstthrough fourth antenna terminals P1, P2, P3 and P4, the first throughfourth switch modules 20, 22, 24 and 26 are within the diameter of thesupport 52.

According to the first through third embodiments illustrated in FIGS. 1,6 and 7, a connection with the four-wire helical antenna devices isconverted by the switch modules such that it can be selected whether allof the power feed phases of the four-wire helical antenna devices aremade the same or are dislocated at intervals of 90 degrees. When thepower feed phases of the four-wire helical antenna devices are the same,transmission and reception of linearly polarized waves for a groundcommunication can be performed. Meanwhile, the power feed phases of thefour-wire helical antenna devices are disclosed at intervals of 90degrees such that reception (or transmission and reception) ofcircularly polarized waves for a satellite communication can beperformed.

As described above, the complex antenna according to the presentinvention corresponds to both a circularly polarized wave and a linearlypolarized wave. Four helical antenna devices are converted by fourswitch modules such that the complex antenna uses a helical antennadevice for a linearly polarized wave and a helical antenna device for acircularly polarized wave in common and the complex antenna can be madesmall.

While this invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims. The preferred embodimentsshould be considered in descriptive sense only and not for purposes oflimitation. For example, even though the sizes, shapes, arrangementrelationships and materials of elements such as antenna devices, switchmodules, delay lines, a cylindrical dielectric, a support and a PCBwhich constitute the complex antenna, are designed by one of ordinaryskilled in the art in various forms, they are included in the presentinvention as long as they are within the scope of the present invention.

1. A complex antenna comprising: a substrate; a power feed terminalprovided at a side of the substrate; four helical antenna devicesdisposed on the substrate at intervals of 90 degrees centering on afirst axis perpendicular to the substrate; four delay lines havinglengths that differ from each other by a quarter wavelength; and fourswitch modules which are connected to the power feed terminal in commonand each of which is connected to a respective helical antenna deviceand a respective delay line, wherein each switch module selects one of afirst mode in which the power feed terminal and each helical antennadevice are directly connected and a second mode in which each delay lineis connected to each helical antenna device so that a power feed phasefeed from the power feed terminal and propagated to each delay line issequentially shifted by 90 degrees.
 2. The complex antenna of claim 1,wherein a linearly polarized wave is transmitted or received in thefirst mode and a circularly polarized wave is transmitted or received inthe second mode.
 3. The complex antenna of claim 2, wherein each switchmodule includes a first switch terminal connected to the power feedterminal, a second switch terminal connected to each helical antennadevice, a third switch terminal connected to a first end of each delayline, and a fourth switch terminal connected to a second of each delayline, and further wherein the first switch terminal and the second endswitch terminal are connected in the first mode, and concurrently, thefirst switch terminal and the third switch terminal are connected in thesecond mode and the second switch terminal and the fourth switchterminal are connected in the second mode.
 4. The complex antenna ofclaim 1, wherein the delay lines are provided on the substrate.
 5. Thecomplex antenna of claim 1, wherein the switch modules are provided onthe substrate.
 6. The complex antenna of claim 1, wherein the helicalantenna devices are thin plate-shaped conductors.
 7. The complex antennaof claim 1, wherein an attenuator is connected to at least one delayline.
 8. The complex antenna of claim 1, wherein a diameter of thesubstrate is in the range of one to three times of an outer diameter ofa spiral formation of each helical antenna device.
 9. The complexantenna of claim 1, further comprising a cylindrical dielectric, whereineach helical antenna device is wound around the dielectric in a spiralshape.
 10. The complex antenna of claim 9, wherein each switch module iswithin a diameter of the dielectric.
 11. The complex antenna of claim 9,wherein a linearly polarized wave is transmitted or received in thefirst mode and a circularly polarized wave is transmitted or received inthe second mode.
 12. The complex antenna of claim 11, wherein eachswitch module includes a first switch terminal connected to the powerfeed terminal; a second switch terminal connected to each helicalantenna device; a third switch terminal connected to a first end of eachdelay line; and a fourth switch terminal connected to a second end ofeach delay line, and further wherein the first switch terminal and thesecond switch terminal are connected in the first mode, andconcurrently, the first switch terminal and the third switch terminalare connected in the second mode and the second switch terminal and thefourth switch terminal are connected in the second mode.
 13. The complexantenna of claim 9, wherein an attenuator is connected to at least onedelay line.
 14. The complex antenna of claim 9, wherein a diameter ofthe substrate is in the range of one time to three times of an outerdiameter of a spiral of each helical antenna device.
 15. The complexantenna of claim 1, further comprising a cylindrical mesh support formedof an insulator, wherein each helical antenna device is wound around themesh support.
 16. The complex antenna of claim 15, wherein each switchmodule is accommodated in the mesh support.
 17. The complex antenna ofclaim 15, wherein a linearly polarized wave is transmitted or receivedin the first mode and a circularly polarized wave is transmitted orreceived in the second mode.
 18. The complex antenna of claim 17,wherein each switch module comprises a first switch terminal connectedto the power feed terminal, a second switch terminal connected to eachhelical antenna device, a third switch terminal connected to one end ofeach delay line, and further wherein a fourth switch terminal connectedto the other end of each delay line, and the first switch terminal andthe second switch terminal are connected in the first mode, andconcurrently, the first switch terminal and the third switch terminalare connected in the second mode and simultaneously, the second switchterminal and the fourth switch terminal are connected in the secondmode.
 19. The complex antenna of claim 15, wherein an attenuator isconnected to at least one delay line.
 20. The complex antenna of claim15, wherein a diameter of the substrate is in the range of one time tothree times of an outer diameter of a spiral formation of each helicalantenna device.